/*
 * Copyright (c) 2000-2004 Niels Provos <provos@citi.umich.edu>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef _EVHTTP_H_
#define _EVHTTP_H_

#include <event.h>

#ifdef __cplusplus
extern "C"
  {
#endif

#ifdef WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <winsock2.h>
#undef WIN32_LEAN_AND_MEAN
#endif

    /** @file evhttp.h
     *
     * Basic support for HTTP serving.
     *
     * As libevent is a library for dealing with event notification and most
     * interesting applications are networked today, I have often found the
     * need to write HTTP code.  The following prototypes and definitions provide
     * an application with a minimal interface for making HTTP requests and for
     * creating a very simple HTTP server.
     */

    /* Response codes */
#define HTTP_OK			200
#define HTTP_NOCONTENT		204
#define HTTP_MOVEPERM		301
#define HTTP_MOVETEMP		302
#define HTTP_NOTMODIFIED	304
#define HTTP_BADREQUEST		400
#define HTTP_NOTFOUND		404
#define HTTP_SERVUNAVAIL	503

    struct evhttp;

    struct evhttp_request;

    struct evkeyvalq;

    /** Create a new HTTP server
     *
     * @param base (optional) the event base to receive the HTTP events
     * @return a pointer to a newly initialized evhttp server structure
     */

    struct evhttp *evhttp_new (struct event_base *base);

    /**
     * Binds an HTTP server on the specified address and port.
     *
     * Can be called multiple times to bind the same http server
     * to multiple different ports.
     *
     * @param http a pointer to an evhttp object
     * @param address a string containing the IP address to listen(2) on
     * @param port the port number to listen on
     * @return a newly allocated evhttp struct
     * @see evhttp_free()
     */
    int evhttp_bind_socket (struct evhttp *http, const char *address, u_short port);

    /**
     * Free the previously created HTTP server.
     *
     * Works only if no requests are currently being served.
     *
     * @param http the evhttp server object to be freed
     * @see evhttp_start()
     */
    void evhttp_free (struct evhttp* http);

    /** Set a callback for a specified URI */
    void evhttp_set_cb (struct evhttp *, const char *,
                        void (*) (struct evhttp_request *, void *), void *);

    /** Removes the callback for a specified URI */
    int evhttp_del_cb (struct evhttp *, const char *);

    /** Set a callback for all requests that are not caught by specific callbacks
     */
    void evhttp_set_gencb (struct evhttp *,
                           void (*) (struct evhttp_request *, void *), void *);

    /**
     * Set the timeout for an HTTP request.
     *
     * @param http an evhttp object
     * @param timeout_in_secs the timeout, in seconds
     */
    void evhttp_set_timeout (struct evhttp *, int timeout_in_secs);

    /* Request/Response functionality */

    /**
     * Send an HTML error message to the client.
     *
     * @param req a request object
     * @param error the HTTP error code
     * @param reason a brief explanation of the error
     */
    void evhttp_send_error (struct evhttp_request *req, int error,
                            const char *reason);

    /**
     * Send an HTML reply to the client.
     *
     * @param req a request object
     * @param code the HTTP response code to send
     * @param reason a brief message to send with the response code
     * @param databuf the body of the response
     */
    void evhttp_send_reply (struct evhttp_request *req, int code,
                            const char *reason, struct evbuffer *databuf);

    /* Low-level response interface, for streaming/chunked replies */
    void evhttp_send_reply_start (struct evhttp_request *, int, const char *);
    void evhttp_send_reply_chunk (struct evhttp_request *, struct evbuffer *);
    void evhttp_send_reply_end (struct evhttp_request *);

    /**
     * Start an HTTP server on the specified address and port
     *
     * DEPRECATED: it does not allow an event base to be specified
     *
     * @param address the address to which the HTTP server should be bound
     * @param port the port number on which the HTTP server should listen
     * @return an struct evhttp object
     */

    struct evhttp *evhttp_start (const char *address, u_short port);

    /*
     * Interfaces for making requests
     */
    enum evhttp_cmd_type { EVHTTP_REQ_GET, EVHTTP_REQ_POST, EVHTTP_REQ_HEAD };

    enum evhttp_request_kind { EVHTTP_REQUEST, EVHTTP_RESPONSE };

    /**
     * the request structure that a server receives.
     * WARNING: expect this structure to change.  I will try to provide
     * reasonable accessors.
     */

    struct evhttp_request
      {
#if defined(TAILQ_ENTRY)
        TAILQ_ENTRY (evhttp_request) next;
#else

        struct
          {

            struct evhttp_request *tqe_next;

            struct evhttp_request **tqe_prev;
          }       next;

#endif

        /* the connection object that this request belongs to */

        struct evhttp_connection *evcon;
        int flags;
#define EVHTTP_REQ_OWN_CONNECTION	0x0001
#define EVHTTP_PROXY_REQUEST		0x0002

        struct evkeyvalq *input_headers;

        struct evkeyvalq *output_headers;

        /* address of the remote host and the port connection came from */
        char *remote_host;
        u_short remote_port;

        enum evhttp_request_kind kind;
        enum evhttp_cmd_type type;

        char *uri;			/* uri after HTTP request was parsed */

        char major;			/* HTTP Major number */
        char minor;			/* HTTP Minor number */

        int got_firstline;
        int response_code;		/* HTTP Response code */
        char *response_code_line;	/* Readable response */

        struct evbuffer *input_buffer;	/* read data */
        ev_int64_t ntoread;
        int chunked;

        struct evbuffer *output_buffer;	/* outgoing post or data */

        /* Callback */
        void (*cb) (struct evhttp_request *, void *);
        void *cb_arg;

        /*
         * Chunked data callback - call for each completed chunk if
         * specified.  If not specified, all the data is delivered via
         * the regular callback.
         */
        void (*chunk_cb) (struct evhttp_request *, void *);
      };

    /**
     * Creates a new request object that needs to be filled in with the request
     * parameters.  The callback is executed when the request completed or an
     * error occurred.
     */

    struct evhttp_request *evhttp_request_new (
            void (*cb) (struct evhttp_request *, void *), void *arg);

    /** enable delivery of chunks to requestor */
    void evhttp_request_set_chunked_cb (struct evhttp_request *,
                                        void (*cb) (struct evhttp_request *, void *) );

    /** Frees the request object and removes associated events. */
    void evhttp_request_free (struct evhttp_request *req);

    /**
     * A connection object that can be used to for making HTTP requests.  The
     * connection object tries to establish the connection when it is given an
     * http request object.
     */

    struct evhttp_connection *evhttp_connection_new (
            const char *address, unsigned short port);

    /** Frees an http connection */
    void evhttp_connection_free (struct evhttp_connection *evcon);

    /** sets the ip address from which http connections are made */
    void evhttp_connection_set_local_address (struct evhttp_connection *evcon,
        const char *address);

    /** Sets the timeout for events related to this connection */
    void evhttp_connection_set_timeout (struct evhttp_connection *evcon,
                                        int timeout_in_secs);

    /** Sets the retry limit for this connection - -1 repeats indefnitely */
    void evhttp_connection_set_retries (struct evhttp_connection *evcon,
                                        int retry_max);

    /** Set a callback for connection close. */
    void evhttp_connection_set_closecb (struct evhttp_connection *evcon,
                                        void (*) (struct evhttp_connection *, void *), void *);

    /**
     * Associates an event base with the connection - can only be called
     * on a freshly created connection object that has not been used yet.
     */
    void evhttp_connection_set_base (struct evhttp_connection *evcon,
                                     struct event_base *base);

    /** Get the remote address and port associated with this connection. */
    void evhttp_connection_get_peer (struct evhttp_connection *evcon,
                                     char **address, u_short *port);

    /** The connection gets ownership of the request */
    int evhttp_make_request (struct evhttp_connection *evcon,
                             struct evhttp_request *req,
                             enum evhttp_cmd_type type, const char *uri);

    const char *evhttp_request_uri (struct evhttp_request *req);

    /* Interfaces for dealing with HTTP headers */

    const char *evhttp_find_header (const struct evkeyvalq *, const char *);
    int evhttp_remove_header (struct evkeyvalq *, const char *);
    int evhttp_add_header (struct evkeyvalq *, const char *, const char *);
    void evhttp_clear_headers (struct evkeyvalq *);

    /* Miscellaneous utility functions */


    /**
      Helper function to encode a URI.

      The returned string must be freed by the caller.

      @param uri an unencoded URI
      @return a newly allocated URI-encoded string
     */
    char *evhttp_encode_uri (const char *uri);


    /**
      Helper function to decode a URI.

      The returned string must be freed by the caller.

      @param uri an encoded URI
      @return a newly allocated unencoded URI
     */
    char *evhttp_decode_uri (const char *uri);


    /**
     * Helper function to parse out arguments in a query.
     * The arguments are separated by key and value.
     * URI should already be decoded.
     */
    void evhttp_parse_query (const char *uri, struct evkeyvalq *);


    /**
     * Escape HTML character entities in a string.
     *
     * Replaces <, >, ", ' and & with &lt;, &gt;, &quot;,
     * &#039; and &amp; correspondingly.
     *
     * The returned string needs to be freed by the caller.
     *
     * @param html an unescaped HTML string
     * @return an escaped HTML string
     */
    char *evhttp_htmlescape (const char *html);

#ifdef __cplusplus
  }

#endif

#endif /* _EVHTTP_H_ */
